To understand the significance and value of the F-35, and whether “it works” or not, cut through the complexity and noise. Simplify. Put aside the politicians, the ideologues, the self-proclaimed experts and listen to the voice of the pilots.

The pilots will take the aircraft into combat, their own lives in the balance as they penetrate contested space and are likely to be outnumbered by adversary aircraft.

Second Line of Defense and a handful of journalists recently had the opportunity to visit with four such pilots during a “Proof of Concept” demonstration on the USS America, November 19, 2016...

On a personal level as pilots, coming from other platforms and stepping into the F-35, do you have an “aha” moment that you can share?

Guts: My first “aha” moment was a seemingly simple thing.

I was executing a familiarization flight near MCAS Yuma. I was coming back to the airfield and I basically just turned the jet and pointed its nose at Yuma.

Immediately the jet is providing me the information of all the traffic that is out there in the airspace.

When I talk to approach for the first time they are telling me about the traffic that is out there that I already know about and I see it.

I can tell who everybody is that he is talking about and the jet also saw traffic that ATC hadn’t seen yet and I asked about it. And I thought, “holy cow,” here I am coming back to the field from a simple familiarity mission and my jet is telling me everything about the operational environment I am about to go into.

In this case, something very simple, the traffic pattern coming back there, but I didn’t have to do anything to have that level of SA.

I can start making decisions about what altitude I wanted to go to, if I wanted to turn left or right, speed up or slow down.

There’s somebody coming up next to me, I want to get in front of them – or whatever.

It is a very simple example, but I thought WOW this is amazing that I see everything and can do that.

The other was the first time I vertically recovered the airplane. The flight control law that the airplane has is unbelievable and I always tell the anecdote. Flying AV-8B Harrier IIs, I only had one specific aircraft I felt like I could kind of go easy on the controls and it would sit there and hover.

I love the Harrier, love flying that aircraft, but there was work involved to bring it back for a vertical landing. The very first time I hovered an F-35B I thought, I am the problem here, and I am just going to let the jet do what it wants to do.

The F-35 was hovering better than I could ever hover a Harrier without doing a thing. That’s back to that workload comment I said earlier. I am performing a vertical landing, and I have the time to look around and see what is taking place on the pad and around me. It is a testament to the jet.

BC: I was conducting a strike mission and Red Air was coming at me. In a 4th Gen fighter you must do a whole lot of interpretation. You see things in azimuth, and you see things in elevation. In the F-35 you just see the Gods eye view of the whole world. It’s very much like you are watching the briefing in real time.

I am coming in to perform the simulated weapons release, and Red Air is coming the other direction.

I have enough situational awareness to assess whether Red Air is going to be a factor to me by the time I release the weapon. I can make the decision, I’m going to go to the target, I’m going to release this weapon.

At the same time I pre-target the threat, and as soon as I release the A2G weapon, I can flip a switch with my thumb and shoot the Red Air.

This is difficult to do in a 4th Gen fighter, because there is so much manipulation of systems in the cockpit.

All while paying attention to the basic mechanics of flying the airplane and interpreting threat warnings that are often very vague, or only directional.

In the F-35 I know where the threats are, what they are and I can thread the needle. I can tell that the adversary is out in front of me and I can make a very, very smart decision about whether to continue or get out of there. All that, and I can very easily switch between mission sets.

Mo: I was leading a four ship of F-35s on a strike against 4th Gen adversaries, F-16s and F/A-18s.

We fought our way in, we mapped the target, found the target, dropped JDAMs on the target and turned around and fought our way out.

All the targets got hit, nobody got detected, and all the adversaries died. I thought, yes, this works, very, very, very well.

Never detected, nobody had any idea we were out there.

A second moment was just this past Thursday. I spent a fair amount of my life as a tail hook guy – [landing F/A-18s on US Navy Supercarriers] on long carrier deployments.

The last 18 seconds of a Carrier landing are intense. The last 18 seconds of making a vertical landing on this much smaller USMC Assault Carrier – is a lot more relaxed.

The F-35C is doing some great stuff. Making a vertical landing [my first this week] on the moving ship, that is much smaller than anything I’ve landed on at sea – with less stress, was pretty awesome.

Sack: It was my first flight at Edwards AFB Jan ’16. I got in the airplane and started it up. I was still on the deck and there were apparently other F-35s airborne – I believe USAF, I was not aware. I was a single ship, just supposed to go out and get familiar flying the aircraft.

As the displays came alive there were track files and the SA as to what everyone else was doing in the airspace, and I was still on the ground. I mean, I hadn’t even gotten my take-off clearance yet.

I didn’t even know where it was coming from. It was coming from another F-35. The jet had started all the systems for me and the SA was there. That was a very eye opening moment for me.

The second one, took place when I came back from that flight. In a Hornet you would pull into the line and had a very methodical way in which you have to shut off the airplane and the systems otherwise you could damage something.

So you have to follow a sequence, it is very methodical about which electronic system you shut off. In the F-35 you come back, you do a couple things then you just shut the engine off, and it does everything else for you. Sounds simple, even silly – but it is a quantum shift

I saw this a week or two ago in a (possibly different) video, but didn't take the time to try to screenshot the frame and post.

This is the first view up the tailpipe I've seen of the F135 engine. IMO we are seeing the aft end of the low pressure turbine. I think the term "radar blockers" is misleading. I can't think of sticking some fixed thing in the back end of a turbojet or turbofan engine that would "block radar" without also wreaking havoc on the flow qualities of the engine exhaust and hence the thermodynamics and the efficiency of the engine.

The objects extending radially from the conical hub at the center of the engine appear consistent with vanes such as you see on an old fashioned wind mill on a farm. That is, they sure look like low pressure turbine vanes. I suppose you could put something in the back designed to "deflect radar" -- bounce the radar into the sides of the engine and shape the engine to try to trap the radar inside the engine similar to how the air intakes are shaped to also trap radar -- but let it spin around like a wind mill. Still, if you don't extract any energy from the "spinning", you are just creating blockage / drag inside the engine.

So IMO this is the rear of the low pressure turbine. And I expect shaping has been applied to the rear of the turbine, possibly to the consternation of the engine fluid dynamicists, to deflect radar into the engine sidewall, which itself has been shaped to "trap" radar reflections in the engine itself. I would also guess that some sort of ceramic coating(s), probably high in iron ferrites, have been applied to the rear of the low pressure turbine blades along with the interior of the back of the engine, to absorb the radar. The conical-shaped hub at the center of the engine is probably also shaped to reflect radar into the engine sidewall to prevent it from reflecting back out the end of the engine. Shaping the aft end of the engine to "trap" radar would be consistent with some statements from pilots and others that the F-35 possesses true all-aspect stealth.

I would not be surprised to learn that the Skunk Works guys "coached up" or otherwise assisted the P&W engineers in stealthifying their motors, as their relationship dates back to at least 1995 when LM entered into an exclusive arrangement with P&W whereby P&W would only work with LM on a shaft-driven lift fan engine.

Lastly, notably absent is a lack of afterburner flame holder structure in the aft end of the motor. I seem to recall videos of multi-stage afterburners lighting off. (I may be recalling a video sequence of an F-14 catapult launch in Topgun where you see multiple stages of the afterburner lighting. Now I cannot recall what I saw looking in the back of an F-16 at an airshow... Do F-100 / F-110 / modern 4th gen afterburning jet engines have some sort of flameholder structure in the back of the engine related to afterburner usage? If so, I would think that would be a radar reflector par excellence.

Several posts / papers have noted that the F135 implemented the afterburner in a new manner to avoid radar signature problems.

Take an F-16, stir in A-7, dollop of F-117, gob of F-22, dash of F/A-18, sprinkle with AV-8B, stir well + bake. Whaddya get? F-35.

The only decent pic of a F135 cutaway is this one which shows the burners coming after the last LP turbine. Has anyone ever made them come before the turbines before? Looking at other engine cutaways I have yet to fine ones with such large blades as the last stage as in the F135 pic above.

For a comparison, here is the F100

One last question... In the above pic that I posted, is the F35 engine on since there are no hold-down chains and it's not under tow?

Last edited by SpudmanWP on 07 Dec 2016, 20:04, edited 1 time in total.

If you find any additional papers by the author, please post them. (I don't have time at present to run off performing exhaustive technical report searches.)

The paper was written in 2010. It described performing CFD analyses of the interactions between ship flowfield (air, not water) wakes and aircraft: an L-class ship + F-35, and a DDG-class ship + H-60. The paper stated they were successful in various modeling endeavors, but no results were presented. The CFD analyses were being performed to develop the capability to incorporate real-time interaction between a ship and aircraft within a running flight simulation. The paper also described using CFD results to inform WOD limits.

I saw lots of pretty pictures, and descriptions of neato analyses, but did not see any results (e.g pretty graphcs of results let alone hard numbers.)

Nothing related to the thermal environment of F-35 exhaust as it may have interacted with the deck and/or other shipboard equipment.

It's been 5-6 years since this paper... so I suspect there are other papers out there. Would be interesting to see what has been published. Maybe I'll search for them later this week if I have the time.

Take an F-16, stir in A-7, dollop of F-117, gob of F-22, dash of F/A-18, sprinkle with AV-8B, stir well + bake. Whaddya get? F-35.

Yes I like pretty pictures and I could have posted more text (abstract) to inform potential readers of content. One will always be disappointed by the amount of public info available online about the F-35 for good reason one would imagine. Chinese / Russian hackers eat sh*t and die! However that article does show some effort (as you say there will be more effort to find probably) into modelling and preparing for F-35 ops generally. The person who said prepare for 1,700 degree exhaust from the F-35 should also es&d but they were probably just ignorantly incompetent & I hope hackers flustered.

The very next article was/is perhaps more interesting however I ran out of puff arranging the pretty picture - it is titled and it does not mention temperature so do not be disappointed by content with 11 page PDF attached:

Computational Modeling of Geometrically Complex Modern Weapons Bays and Weapons Dispense at High Supersonic SpeedsRudy Johnson; US Air Force Research Laboratory, Air Vehicles Directorate (AFRL/RB), Wright-Patterson AFB, OH

"ABSTRACTComputational modeling of the air flow in a geometrically-complex weapons bay, as well as the separation of weapons from a generic cavity model into a high-Mach (3.5–5.0) -, are summarized. Computational work on the geometrically-complex bay is focused on flow control strategies for the reduction of dynamic pressure loads. Results indicate significantly different acoustic characteristics for the bay when one versus two doors is open. When both bay doors are open, leading-edge mass blowing combined with aft-wall treatment is an effective approach to reduction of dynamic pressure loads. However, the effectiveness of this control strategy is reduced when only one bay door is open, due to the generation of strong resonant tones. Computational fluid dynamics (CFD) analysis has led to the development of novel, easily integratable “passive” control strategies involving “baffles” that have shown significant reduction in the tonal amplitude. The CFD simulations have enabled a good understanding of the complex flow field, led to the development of control strategies, and have guided the sub-scale wind-tunnel test program. Significance to the Department of Defense (DoD) is the integration of successful acoustic reduction concepts into realistic aircraft weapons bays.

CFD simulations of weapons separation from a generic bay at high-speed are being used to develop data acquisition techniques for sub-scale wind-tunnel testing in the high supersonic regime. The bays at these high-Mach numbers involve spatial and temporal flow field scales that are an order-of-magnitude smaller than those at Mach 1.5–2.0 regime, making the numerical simulations of such bays computationally more expensive. The availability of the high performance computing resources towards this end is gratefully acknowledged, while the significance to DoD is the improved understanding of the associated flow physics that will help in the better design of data acquisition techniques for store dispense at these high supersonic Mach numbers."